Vascular Contribution to Alzheimer's Disease — Beyond Amyloid

Vascular Contribution to Alzheimer's Disease

Overview

This experiment addresses the AD Knowledge Gap: "How do vascular factors contribute to AD?" (ranked in top 15 AD gaps). Vascular dysfunction interacts with amyloid pathology and may be an independent driver of cognitive decline.

Related: [AD Knowledge Gap #12](/mechanisms/ad-knowledge-gaps-ranked) | [AD Cure Roadmap](/mechanisms/ad-cure-roadmap) | [Neurovascular Unit](/mechanisms/neurovascular-unit)

Key Question

Vascular Contribution to Alzheimer's Disease

Overview

This experiment addresses the AD Knowledge Gap: "How do vascular factors contribute to AD?" (ranked in top 15 AD gaps). Vascular dysfunction interacts with amyloid pathology and may be an independent driver of cognitive decline.

Related: [AD Knowledge Gap #12](/mechanisms/ad-knowledge-gaps-ranked) | [AD Cure Roadmap](/mechanisms/ad-cure-roadmap) | [Neurovascular Unit](/mechanisms/neurovascular-unit)

Key Question

What is the independent contribution of vascular dysfunction to AD pathogenesis? Can targeting vascular pathways provide additive benefits beyond anti-amyloid therapy?

Hypothesis

Vascular dysfunction contributes to AD through:

Study Design

Vascular-AD Cohort Study

Recruit 600 participants with:

| Group | N | Characteristics |
|-------|---|-----------------|
| AD + CVD | 200 | AD with confirmed cerebrovascular disease |
| AD only | 200 | AD without significant vascular disease |
| CVD only | 100 | Vascular cognitive impairment, no AD |
| Control | 100 | Normal cognition, no vascular disease |

Assessment Battery

• Neuroimaging: MRI (white matter hyperintensities, microbleeds), DSC-MRI (CBF), DTI
• Cerebrovascular: Carotid ultrasound, transcranial Doppler
• Fluid biomarkers: VEGF, sFlt-1, PDGF-BB, Aβ42/40, p-tau
• Cognitive testing: CDR, MMSE, neuropsychological battery

Validation Protocol

Phase 1: Cross-sectional Analysis (Months 1-12)

Primary measures:

• CBF mapping (arterial spin labeling)
• BBB permeability (dynamic contrast-enhanced MRI)
• White matter integrity (DTI)
• Correlation with cognitive performance

Phase 2: Longitudinal Trajectory (Months 12-36)

Follow-up: 24 months, 4 timepoints

Key questions:

• Does vascular burden predict faster cognitive decline independent of amyloid?
• Do vascular interventions (BP control, statins) slow decline in AD patients?
• Is there synergy between vascular and amyloid pathology?

Phase 3: Intervention Study (Months 24-48)

Trial design: 2x2 factorial

| Arm | Intervention |
|-----|--------------|
| A | Standard of care |
| B | Intensive vascular risk control |
| C | Anti-amyloid (lecanemab) |
| D | Intensive vascular + anti-amyloid |

Primary endpoint: Cognitive decline rate (CDR-SB slope)

Expected Outcomes

Hypothesis 1: Vascular as Independent Driver

• Vascular burden predicts cognitive decline independent of amyloid
• Deliverable: Vascular risk score for AD prognosis

Hypothesis 2: Vascular-Amyloid Synergy

• Combined pathology > sum of individual effects
• Deliverable: Combination therapy targeting both pathways

Hypothesis 3: Vascular as Amyloid Cofactor

• Vascular changes facilitate amyloid deposition
• Deliverable: Prevention strategy targeting vascular health

Critical Readouts

• CBF reduction: When does it occur relative to amyloid?
• BBB breakdown: Correlation withCSF/plasma albumin ratio
• Treatment response: Does vascular care improve anti-amyloid outcomes?

Model Systems

| System | Use | Strength |
|--------|-----|----------|
| Human cohort | Primary data | Direct relevance |
| 5xFAD x cerebral ischemia model | In vivo | Combined pathology |
| iPSC brain microvascular organoids | Mechanism | Human BBB model |
| Rodent chronic hypoperfusion model | Vascular | Established model |

Feasibility Assessment

| Factor | Assessment |
|--------|------------|
| Technical Feasibility | High — MRI, biomarkers established |
| Recruitment Feasibility | Moderate — stroke clinics, memory clinics |
| Cost Estimate | $12-18M over 4 years |
| Timeline | 48 months |
| Cross-Disease Value | High — applies to vascular dementia, PD |

Cost Breakdown

| Component | Cost (USD) |
|-----------|-------------|
| Clinical operations | $6M |
| MRI (2500 scans) | $3M |
| Biomarker assays | $3M |
| Data analysis | $2M |
| Intervention supplies | $2M |

Risk Analysis

| Risk | Mitigation |
|------|------------|
| Confounding by comorbidities | Careful exclusion criteria |
| Variable vascular assessment | Standardized protocols |
| Intervention interactions | Factorial design |

Cross-Links

• [Neurovascular Unit](/mechanisms/neurovascular-unit)
• [Cerebral Amyloid Angiopathy](/gaps/cerebral-amyloid-angiopathy-ad)
• [AD Combination Therapy Matrix](/therapeutics/ad-combination-therapy-matrix)
• [AD Knowledge Gaps](/mechanisms/ad-knowledge-gaps-ranked)
• [Experiment Priority Index](/experiments/experiment-priority-index)